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Vinod Kumar Vavilapalli commented on YARN-4353:
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[~templedf], added you to the YARN contributors list, so you should be able to assign this
and any future tickets to yourselves from now on.
Regarding this JIRA, a lots of places in NM *do* depend on the user/group information, so
we should be extra careful about how we do this. I get a feeling there is an alternative fool-proof
approach for this - do the getGroups call once in the NodeManager and pass it down everywhere
so we don't repeatedly do it downstream.
> Provide short circuit user group mapping for NM/AM
> --------------------------------------------------
>
> Key: YARN-4353
> URL: https://issues.apache.org/jira/browse/YARN-4353
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: nodemanager
> Affects Versions: 2.7.1
> Reporter: Daniel Templeton
>
> When the NM launches an AM, the {{ContainerLocalizer}} gets the current user from {{UserGroupInformation}},
which triggers user group mapping, even though the user groups are never accessed. If secure
LDAP is configured for group mapping, then there are some additional complications created
by the unnecessary group resolution. Additionally, it adds unnecessary latency to the container
launch time.
> To address the issue, before getting the current user, the {{ContainerLocalizer}} should
configure {{UserGroupInformation}} with a null group mapping service that quickly and quietly
returns an empty group list for all users.
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